Square D Company

Clark L Oster

Eugene W Wehr

Joseph M Khalid

James W Dickens

Donald R Venzke

Paul J Rustebakke

James A Tharp

James W Cook

Daniel R Schiefen

Terence J Evans

A circuit breaker is provided having a stationary contact, a movable contact and a blade which has a first end and a second end. The movable contact is secured to the first end of the blade. The blade is rotatable about a pin between a BLOWN OPEN position and a CLOSED position, wherein the movable contact is separated from the stationary contact when the blade is in the BLOWN OPEN position and the movable contact engages the stationary contact when the blade is in the CLOSED position. The blade further has a protrusion portion extending from its second end. The circuit breaker further includes a catcher rotatably coupled to a pivot pin and having a nose portion for engagement with the blade protrusion portion. A spring is mounted about the pivot pin and engages the catcher for biasing the catcher towards the blade whereby the nose portion rests against the protrusion portion of the blade when the blade is in the CLOSED position and the nose portion overlaps the protrusion portion when the blade is in the BLOWN OPEN position thereby holding the blade in the BLOWN OPEN position.

Current limiting circuit breaker operating mechanism

A circuit breaker (51) includes an arc stack of metal plates (52), each of which is disposed parallel to the movement of the contact arm (12), whereby lug strikes which may pass through the vent holes (32) in the housing (16) to the lug (18) are avoided. The arrangement of the metal plates (52) provides protection from such unintended lug strikes without requiring the use of additional parts (e.g., barriers, insulators, and deflectors). A contact arm (12) is provided that is light in mass, but which is still strong enough to resist bending caused by the contact blow off loop forces which occur during fault conditions. Contact arms (12) which have I-beam construction, as well as hollow cylindrical and hollow polygonal construction are capable of carrying currents found in intermediate range circuit breakers; however, they are lighter in mass than solid contact arms and thereby enable faster contact separation and reduced arcing currents.

Effective arc stack/efficient contact carrier

A circuit breaker line terminal includes a uniform width, flat, sheet metal body having end portions for coupling to a line conductor and an arc runner, respectively. An integral tongue has an end forming a return loop spaced from the body and includes a lanced out portion that carries a contact. The contact may be supported through the opening formed by lancing the body.

Line terminal and arc stack for a circuit breaker

A circuit breaker for breaking current conduction between line and load connectors in response to tripping of a bimetallic thermal element as a result of an over-current condition is disclosed. According to the invention, a trip crossbar is permitted to translate as well as rotate to relieve stress on the thermal element.

Trip crossbar translation to prevent bimetal overstressing in a circuit

Apparatus for simultaneously applying two independent forces to the contact blades of a movable contact assembly. The contact assembly has three contact blades joined at the base. The circuit breaker mechanism exerts a closing force through a blade carrier to the center blade which in turn exerts a closing force on the outer main blades. To increase the contact force on the outside main blade contacts without increasing the contact force of the center blade contact and without changing the relative distances between the blade carrier and the main blade contacts and center blade contacts, a compression spring is positioned between each main blade and the blade carrier.

Contact assembly for a circuit breaker

An arc suppressing assembly for use in a circuit breaker having at least one pair of separable contacts which includes an arc stack assembly in back-to-back relationship with a baffle assembly with the arc stack assembly in between the baffle assembly and the separablecontacts. The arc stack assembly includes a pair of insulating support legs having a plurality of parallel slots which receive tabs of respective and generally rectangular-shaped arc plates with a recessed front portion of each arc plate facing toward the contacts. The uppermost arc plate is provided with an extending runner portion which attracts an arc formed upon the opening of the contacts under certain current conditions. The baffle assembly similarly includes a pair of insulating side supports with a plurality of parallel slots provided therein to receive tab portions provided on the sides of generally rectangular insulating baffles. The association of the insulating baffles with the metallic arc plates imparts a generally wave-like motion to the venting gases. Each of the plates are at an angle of substantially 22.degree. to the horizontal with the gases first being directed upward by the arc plates and then downward by the baffles. A second set of baffles is provided behind a first column of baffles which are positioned in generally parallel relationship with the arc plates and further assist in the extinguishing and venting of the gases as they are blown away from the contacts.

Arc extinguishing assembly

An improvement to prevent alteration of the circuit breaker calibration due to high overloads. A circuit breaker has a U-shaped current path with a brazed junction at the bend of the 'U'. Upon the occurrence of a large overload, the opposing current in the two legs of the U-shaped path will force the two legs of the 'U' apart, possibly weakening the brazed junction. When one of the legs is a closely calibrated component of a trip assembly, the breaker will no longer operate within the proper range. A stop is placed within the housing to prevent the two legs from moving apart such a distance as will cause the brazed junction to fail.

Circuit breaker improvement to prevent setting of trip assembly

A current limiting circuit breaker having for each pole, a pair of main contacts separable upon operation of a thermally and electromagnetically operable tripping device and a pair of auxiliary contacts for current limiting in series with the main contacts and in parallel with a transformable resistor having a positive temperature coefficient of resistance. The auxiliary contacts are separable when an electromagnet is energized by a fault current which simultaneously energizes a field magnet to produce a transverse magnetic field across the auxiliary contacts and the arc formed between them when separating. This simultaneous action of electromagnet and field magnet coacting for rapid contact separation and lengthening of the arc upon flow of a fault current serves to increase arc voltage almost instantaneously to that of the source, about which time the fault current is totally shunted into the resistor. The auxiliary contacts are carried on a pair of minimum inertia movable contact blades to facilitate rapid separation of the auxiliary contacts. The minimum inertia contact blades are elongated between a pivot point and the point at which the contacts are mounted, where they terminate without providing an arc runner portion.

Current limiting circuit breaker

A current limiting circuit breaker having for each pole, a pair of main contacts separable upon operation of a thermally and electromagnetically operable tripping device and a pair of auxiliary contacts for current limiting in series with the main contacts and in parallel with a transformable resistor having a positive temperature coefficient of resistance. The auxiliary contacts are separable when an electromagnet is energized by a fault current which simultaneously energizes a field magnet to produce a transverse magnetic field across the auxiliary contacts and the arc formed between them when separating. This simultaneous action of electromagnet and field magnet coacting for rapid contact separation and lengthening of the arc upon flow of a fault current serves to increase arc voltage almost instantaneously to that of the source, about which time the fault current is totally shunted into the resistor. An armature and armature pin are mounted for reciprocal movement when the electromagnet is energized. The armature pin is operatively connected to the auxiliary contact blades which are mounted for pivotal movement from a contact closed to a contact open position when the armature and armature pin are attracted by the electromagnet. A compression coil spring encircles the armature pin to bias the auxiliary contact blades toward a normally contact closed position.

A current limiting circuit breaker having for each pole, a pair of main contacts separable upon operation of a thermally and electromagnetically operable tripping device and a pair of auxiliary contacts for current limiting in series with the main contacts and in parallel with a transformable resistor having a positive temperature coefficient of resistance. The auxiliary contacts are separable when an electromagnet is energized by a fault current which simultaneously energizes a field magnet to produce a transverse magnetic field across the auxiliary contacts and the arc formed between them when separating. This simultaneous action of electromagnet and field magnet coacting for rapid contact separation and lengthening of the arc upon flow of a fault current serves to increase arc voltage almost instantaneously to that of the source, about which time the fault current is totally shunted into the resistor. The tripping device for the main contacts includes a main trip lever for latching engagement with an armature, releasable upon energization of a magnetic core due to a fault current. It also includes a second trip lever normally latched by a rotatable trip bar, which is rotated to unlatching position by a bimetal when deflected due to prolonged overload conditions. When the second trip lever is unlatched, it strikes the armature thereby releasing it from latching engagement with the main trip lever allowing the tripping device to open the main contacts.

A current limiting circuit breaker having for each pole, a pair of main contacts separable upon operation of a thermally and electromagnetically operable tripping device and a pair of auxiliary contacts for current limiting in series with the main contacts and in parallel with a transformable resistor having a positive temperature coefficient of resistance. The auxiliary contacts are separable when an electromagnet is energized by a fault current which simultaneously energizes a field magnet to produce a transverse magnetic field across the auxiliary contacts and the arc formed between them when separating. This simultaneous action of electromagnet and field magnet coacting for rapid contact separation and lengthening of the arc upon flow of a fault current serves to increase arc voltage almost instantaneously to that of the source, about which time the fault current is totally shunted into the resistor. One of the main contacts of each pole is carried by a movable contact blade. The contact blades have tapered mounting end portions which extend through an elongated molded plastic crossbar, the movable contact blade for each pole being mounted in spaced apart relation in the common crossbar. A metallic insert is embedded in the molded plastic crossbar, the metallic insert having spaced apart openings located to permit the tapered mounting end of the contact blades to extend therethrough.

Current limiting circuit breaker having for each pole, a pair of main contacts separable upon operation of a thermally and electromagnetically operable tripping device and a pair of auxiliary contacts for current limiting in series with the main contacts and in parallel with a transformable resistor having a positive temperature coefficient of resistance. The auxiliary contacts are separable when an electromagnet is energized by a fault current which simultaneously energizes a field magnet to produce a transverse magnetic field across the auxiliary contacts and the arc formed between them when separating. This simultaneous action of electromagnet and field magnet coacting for rapid contact separation and lengthening of the arc upon flow of a fault current serves to increase arc voltage almost instantaneously to that of the source, about which time the fault current is totally shunted into the resistor. A conductor system is associated with the electromagnet which includes two conductor turns, the first being connected in parallel with the auxiliary contacts and the second being connected in series with the auxiliary contacts and with the other conductor turn. The second produces magnetic flux in the magnet core when a fault current appears and while the auxiliary contacts are closed. The first and second conductor turns together continue to produce magnetic flux in the magnet core after the auxiliary contacts have opened to hold them apart and prevent contact welding.

Growing community of inventors

Cedar Rapids, IA, United States of America

Clark L Oster